Catheter Assembly for Blood Clots Removal

ABSTRACT

A medical device comprises a catheter and an aspiration pump. The catheter has a hybrid reinforcement to improve performance characteristics. The aspiration pump is cycled to improve aspiration efficacy.

RELATED CASES

This application is a Continuation-In-Part of U.S. patent applicationSer. No. 15/557,142, filed on May 4, 2017.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to methods and devices for removingthromboembolic materials and other tissue from human body.

2. Description of the Prior Art

Endovascular catheters have been commonly used to remove thromboembolicblockages and other tissue from endovascular and non-endovascularlocations in the human body. Single-lumen catheters are employed toaspirate a clot from a cerebral vessel, coronary vessels and peripheralvessels. Such procedure in most cases includes placing a distal end/tipof a catheter at the proximal face of the clot and applying vacuum tothe clot via a proximal port of the catheter. Fresh and soft clotusually are easily aspirated, while harder, more organized clot tends toclog the catheter. In such cases, the catheter with trapped clot andunder suction is removed outside the patient. Then, the removed catheteris cleaned and introduced again to the treatment location to continuethe clot removal process if necessary. However, in some cases, the clotis broken up in pieces by mechanical means during catheter removal andmultiple introductions, causing a distal embolization and oftendangerous clinical complications.

The latest development of aspiration devices has significantly improvedrecanalization rates. A direct aspiration, the ADAPT technique forstroke thrombectomy, was recently shown to be an effective and rapid wayto achieve cerebral revascularization. This technique focuses onengaging and removing a clot without the use of ancillary devices andsolely relying on aspiration forces generated by the suction pumpthrough the catheter. While the use of aspiration alone to remove bloodclots has significantly improved in the last several years, a singlepass/use success rate still remains below 75%. Therefore, there is aneed for better aspiration devices which are simple to use, and canquickly and safely remove thromboembolic material.

SUMMARY OF THE DISCLOSURE

There are three approaches to improve efficacy of removing blood clotsusing aspiration with a single lumen aspiration catheter: use ofstronger vacuum pumps to aid in aspiration of the clot through thecatheter, use of larger aspiration catheters; and use of aspirationcatheters with expandable tips.

Currently used air aspiration pumps are reaching almost an absolutevacuum of approximately 29 in-Hg (>14 psi) while aspirating air from ablood collection container with a maximum liquid negative pressure ofaround 27.0 in-Hg. Use of liquid pumps may be beneficial and mayincrease direct blood aspiration to 28+ in-Hg. Another option is toincrease the size (e.g., inner lumen) of the aspiration catheters.Increasing the size of the inner lumen of an aspiration catheter whilemaintaining the same diameter for the outer lumen is challenging becausethis compromises the required performance characteristics for thecatheter, such as, for example, kink resistance. Use of innovativereinforcement may be helpful. Other options include the use a catheterwith a larger frontal aperture.

Cerebral vessels have a complex vessel pattern, and extensive cathetermanipulations with a larger size catheter when accessing and navigatingthese vessels may be risky and may cause vessel dissections,perforations and stroke. However, neuro-interventionists would benefitfrom the availability of catheters that can be easily, quickly andsafely delivered through a standard guide catheter, providing a moreeffective vehicle to aspirate blood clots.

Increasing the inner lumen size of the aspiration catheters is in mostcases related to enlarging the outer size of the catheter, and suchapproach carries challenges to access the treatment sites, potentialclinical complications, and longer procedure time. It is especiallyrisky with the continuous exodus of neurosurgeons to the interventionalNeuro-Radiology Field whose manual skills are not always sufficient forsuch tasks. Therefore, use of aspiration catheters which are easier tonavigate and locate at the treatment site with an improved reinforcementstructure, and/or expandable tips, may present an attractive anddesirable clinical alternative to improve blood clot removal.

The present invention provides alternative options to increase efficacyof clot removal by increasing the flow of removed clots. Increasing theflow within the aspiration catheter may be accomplished by enlarging atleast partially the aspiration lumen by combining two catheters that arealways an integral part of interventional procedures together: theaspiration catheter and a guide catheter or sheath. Merging these twocatheters may be accomplished by placing a modified aspiration catheterhaving a smaller and shorter tubular body within a larger and longerguide catheter, while providing a suitable seal between them foraspiration. Such approach will increase flow within two combinedcatheters and result in more efficient clot aspiration.

Furthermore, such modified extension catheters comprising a short tubeattached to a long pushing/pulling wire may have a larger inner lumencompared with longer conventional aspiration catheters. Thus, such shortextension catheters may considerably minimize challenges with navigatingaspiration catheters to the treatment sites and maneuvering the catheterduring clot-removal.

Additionally, it is also beneficial to provide a larger catheter openingsurface on the distal end of the extension catheter. For example,instead of using a conventional circular aperture on the distal end ofthe aspiration catheter, applying an oval or angulated aperture mayimprove clot removal. A larger opening lumen of the aspiration cathetermay also be achieved by using an expandable tip on the distal end ofaspiration catheter. Such expandable tip may be suitable not only whenimplemented with an extension catheter of the present invention but alsowith any conventional aspiration catheter currently in clinical use.

The present invention comprises a coaxial catheter assembly including aguide catheter or sheath, and a shorter aspiration catheter or anextension catheter for use to remove thromboembolic material from thehuman body. The treatment site may include but is not limited toendovascular locations such as coronary circulation, cerebral and otherperipheral circulation, but may also include non-endovascular locations.The guide catheter is delivered into the body through a standardintroducer with a hemostatic valve utilizing a conventional0.025″-0.038″ guidewire. After the guide catheter or sheath is placedinside the body, a 0.025″-0.038″ guidewire is removed and a smallerguidewire in sizes between 0.008″-0.018″ is placed at the treatmentlocation. All these activities are performed under fluoroscopy or usingother imaging techniques. Once the smaller guidewire is positioned at orthrough the treatment site, the extension catheter is introduced over asmaller guidewire into the guide catheter or sheath to the proximal partof the clot or other tissue to be removed. The distal part of theextension catheter is placed outside the guide catheter while theproximal part of the extension catheter remains inside the guidecatheter. The clot/tissue removal process begins when a suction pumpattached to the proximal end of the guide catheter is activated. Uponactivation of suction, a seal between the guide catheter and theextension catheter is activated and blood clots are aspirated from thetreatment site outside the body.

In one aspect of the present invention, a catheter assembly for bloodclots and other tissue removal comprises a guide catheter having adistal end, a proximal end and a lumen extending longitudinally, and anextension catheter positioned at least partway inside the guidecatheter. The extension catheter includes a distal tubular portion ormember and has an open distal end and an open proximal end. The proximalopen end of the extension catheter is attached to a pushing/pulling wirethat is extended along the inner lumen of the guide catheter and outsidethe proximal end of the guide catheter. The extension catheter mayfreely move inside and outside of the guide catheter.

In one embodiment, the extension catheter has a variable flexibility,being more flexible on the distal end and less flexible on the proximalend.

In another embodiment, the pushing wire is further attached to thedistal end of the extension catheter. The pushing wire may be located inone of the following locations: extended along the main lumen of theextension catheter, placed in a separate lumen within the extensioncatheter, or partially located in both.

The distal tubular portion/member of the extension catheter isconfigured to be extended beyond the distal end of the guide catheterwhile the proximal portion of the tubular member of the extensioncatheter remains within the lumen of the guide catheter. The extensioncatheter portion that remains inside the guide catheter includes atleast partially the tubular member and the attached pushing wire.

The inner lumen of the guide catheter and inner lumen of the extensioncatheter are aligned accordingly to allow contrast injection andaspiration of blood clots and other tissue.

In yet another embodiment, the tubular portion/member of the extensioncatheter may have one of the following openings on the distal andproximal ends, including but not limited to, circular, oval, irregularor any other shape.

In another embodiment, the extension catheter is adopted for insertioninto the proximal end of the guide catheter, can be moved along theentire length of the guide catheter, and may also be at least partiallypositioned outside of the distal end of the guide catheter.

The guide catheter and the extension catheter may be provided inseparate packages, or in one package with two separate devices.

In yet another embodiment, the inner diameter of the guide catheter isat least 0.002″ larger than the outer diameter of the extensioncatheter.

In another embodiment, the extension catheter has a hydrophilic coatingon the outside surface, or a hydrophobic coating on the outside surface,or a combination of both coatings.

In yet another embodiment, a conventional metal pushing/pulling wire isattached to the distal end of the extension catheter, and such wire mayhave a variety of sizes and configurations, including circular, oval,square, flat, irregular and a combination thereof.

In another embodiment, the extension catheter is at least partially madeof one of the following materials, including but not limited topolymers, reinforced polymers, metals, or a combination thereof.

In yet another embodiment, an aspiration feature is attached to theproximal end of the guide catheter and may include any suitable vacuumdevice or machinery attached to the proximal end of the guide catheter,including a hospital line suction, a reusable pump, a disposable pump,syringes and a combination thereof.

In another embodiment, a seal between the guide catheter and theextension catheter is achieved by using a soft tip mounted on the distalend of the guide catheter. When the guide catheter/extension catheter isunder vacuum, the soft tip collapses and squeezes around the extensioncatheter, providing a suitable seal for aspiration of blood clots.

In yet another embodiment, a hydrophilic coating is applied on theexternal surface of the extension catheter to further reduce frictionbetween the extension catheter and the guide catheter and to provide aseal between the guide catheter and the extension catheter.

In another embodiment, a hydrophobic coating is applied on the externalsurface of the extension catheter to further reduce friction between theextension catheter and the guide catheter and to provide a seal betweenthe guide catheter and the extension catheter.

In another aspect of the present invention, a catheter assembly forblood clots and other tissue removal comprises a guide catheter with atleast one longitudinal lumen, and an extension catheter having a tubularmember with a pushing wire attached and positioned through the guidecatheter. The distal end of the tubular member is located outside theguide catheter and the proximal end of the tubular member is locatedinside the guide catheter. A suction source is attached to the proximalend of the guide catheter and provides more than 20 in-Hg aspirationpressure at the distal end of the extension catheter. The extensioncatheter may freely move within the guide catheter when aspiration isapplied.

In another embodiment, the outer surface of the extension catheter has atexture to further enable and support the seal space between the outercatheter and the guide catheter during aspiration. Such textured surfacemay be coated with a hydrophilic coating or hydrophobic coating, orboth. The surface texture may comprise a small local deviation of asurface from the perfectly flat or smooth surface, and include surfaceroughness or waviness.

In another aspect, a catheter assembly for blood clots and other tissueremoval comprises a guide catheter and an extension catheter. The guidecatheter has a distal end, a proximal end and at least one lumenextending longitudinally. A soft tip is provided on the distal end ofthe guide catheter. The extension catheter is positioned through anddistally to the guide catheter such that the proximal end of theextension catheter is located inside the guide catheter. A suctionsource is attached to the proximal end of the guide catheter andprovides aspiration pressure along the guide catheter and the extensioncatheter. During aspiration, a soft tip of the distal end of the guidecatheter collapses around, embraces or surrounds the extension catheter,providing a sufficient seal for aspiration of clots.

In another aspect of the present invention, the presence of blood,saline or contrast may surround the area of the soft tip and furtherprovide a seal between the extension catheter and the guide catheterwhen under aspiration.

In another aspect of the present invention, a catheter assembly forblood clots and tissue removal comprises a guide catheter having atleast one lumen extending longitudinally, and an extension catheterpositioned through and distally to the guide catheter. The distal end ofthe extension catheter is outside the guide catheter and the proximalend of the extension catheter remains inside the guide catheter. Thereis a seal between the extension catheter and guide catheter. A suctionsource attached to the proximal end of the guide catheter providesaspiration pressure along the guide catheter and the extension catheter.The inner lumen along the extension catheter is smaller than the innerlumen within the guide catheter to facilitate the flow of clots.

In yet another aspect of the present invention, a catheter assembly forblood clots and tissue removal comprises a guide catheter having aninner lumen extending longitudinally and an extension catheter having aninner lumen extending longitudinally and at least partially placedthrough the guide catheter. The catheter assembly further includes meansfor sealing space between the extension catheter and the guide catheter.The inner lumen along the guide catheter is larger than the inner lumenalong the extension catheter to increase the flow of blood clots.

In another aspect of the present invention, a catheter assembly forblood clots and tissue removal comprises a guide catheter having aninner lumen extending longitudinally, an extension catheter having atubular portion, and a pushing wire attached to the proximal end of thetubular portion. An expandable tip is located on the distal end of thetubular portion, and the tubular portion of the extension catheter ispositioned at least partially inside of the guide catheter.

In one embodiment, the expandable tip comprises a tubular braid having aproximal end attached to the distal end of the tubular portion of theextension catheter. Such tubular braid is coated with a silicone tosecure a shielded tubular configuration.

In another embodiment, the catheter assembly further includes means forsealing the space between the tubular member of the extension catheterand the guide catheter.

In yet another embodiment, the distal expandable tip opens to a largersize upon release from the guide catheter than its size inside theguiding catheter.

In another embodiment, the tubular member of the extension catheter isconfigured to be pushed through and out of the guide catheter andretrieved back into the guide catheter using the pushing wire.

In yet another embodiment the pushing/pulling wire may be attached tothe tubular braid.

In another embodiment, the tubular braid is configured to have a pre-setexpanded shape when released from the guide catheter and such pre-setexpanded shape may include the following configurations: tubular,funneled, syphoned, coned, tapered or other similar shape that providesat least partial tip expansion of the tubular braid when pushed outsidethe guide catheter.

In another aspect of the present invention, a method for removing bloodclots from a treatment location in patient comprises placing a guidecatheter inside the patient, positioning a guide wire through the guidecatheter at the treatment location, and introducing an extensioncatheter over the guide wire into the guide catheter to the treatmentlocation. The extension catheter comprises a distal tubularportion/member, and a wire attached to the proximal end of the distaltubular portion/member, wherein the distal end of the extension catheteris partially extended beyond the guide catheter while the proximal endof extension catheter is located inside the guide catheter. Finally,blood clots are aspirated outside the patient using suction attached tothe proximal end of the guide catheter.

In another embodiment, the extension catheter may be repositioned duringthe removal of blood clots.

In yet another embodiment, repositioning of the extension catheter isperformed during one of the following steps: when the extension catheterand guide catheter are under vacuum, under no vacuum, and during bothsteps.

In another embodiment, placing the guide catheter includes placing asheath.

In yet another embodiment, there is a seal between the guide catheterand the extension catheter to secure the suction of blood clots from thetreatment location through the extension catheter, through the guidecatheter and outside the patient.

In another embodiment, a seal between the extension catheter and theguide catheter is achieved by a soft tip on the distal end of the guidecatheter, by hydrophilic coating of the extension catheter, byhydrophobic coating of the extension catheter, or by a combinationthereof. In addition, patient blood, contrast and saline may also aid insecuring the seal.

In yet another embodiment, the guidewire is placed beyond blood clotsand remains in place during the removal of blood clots.

In another embodiment, the guidewire is removed from the patient afterplacement of the extension catheter at the treatment site and duringclots removal.

In yet another embodiment, the extension catheter and guide catheter areremoved from the treatment location when the extension catheter getsclogged.

In yet another embodiment, cleaning the extension catheter from clots isperformed outside the patient, and the extension catheter may beintroduced again to the treatment area to continue the removal of bloodclots.

In another embodiment, the guide catheter together with the extensioncatheter are removed outside the patient, cleaned and reintroduced againto continue clot removal.

In another aspect of the present invention, a method for removing bloodclots from a treatment location in patient comprises placing a guidecatheter inside the patient, positioning a guide wire through the guidecatheter at the treatment location, and introducing an extensioncatheter over the guide wire into the guide catheter to the treatmentlocation. The extension catheter comprises a distal tubularportion/member having a distal end and a proximal end, and apushing/pulling wire attached to the proximal end. The distal end of theextension catheter is partially extended beyond the guide catheter whilethe proximal end of extension catheter is located inside the guidecatheter. Finally, blood clots are aspirated outside the patient usingsuction attached to the proximal end of the guide catheter, and whereinthe clot flow within the distal end of the extension catheter is slowerthan within the guide catheter.

In another aspect of the present invention, a method for removing bloodclots and other tissue from patient comprises placing a guide catheterhaving a soft tip inside the patient, positioning a guide wire throughthe guide catheter at the treatment location, introducing an extensioncatheter with an expandable tip over the guide wire into the guidecatheter to the treatment location, and aspirating blood clots outsidethe patient using suction attached to the proximal end of the guidecatheter.

In another embodiment, the distal expandable tip opens to a larger innerlumen upon release from the guide catheter than inside the guidingcatheter, so as to increase the efficacy of the removal of clots.

In another embodiment, the tubular member of the extension catheter isconfigured to be pushed through and out of the guide catheter. andretrieved back into the guide catheter using the pushing wire beforeblood clots removal, during blood clot removal, and during a combinationof both.

In yet another embodiment, the tubular braid is suitable to assume apre-set expanded shape having a larger distal inner lumen than theproximal lumen when pushed outside of the guide catheter.

In another aspect of the present invention, a device comprising anaspiration catheter and a liquid cycling aspiration pump are provided toincrease efficacy of clot removal.

In yet another aspect of the present invention, an endovascular catheterincludes an elongate flexible catheter body having a proximal end, adistal end and a side wall defining a central lumen. The side wallincludes a tubular inner liner and a hybrid reinforcement that includesa helical coil and a braid. An outer jacket encloses the hybridreinforcement and is formed from a plurality of tubular segmentspositioned end to end, coaxially along the hybrid reinforcement.

In yet another aspect of the present invention, the flexural loadprofile along the length of the catheter is configured to provideenhanced distal flexibility, overall pushability and back up supportwhile minimizing the overall wall thickness of the catheter having awall thickness ratio with the catheter inner diameter to catheter outerdiameter that is higher than 0.80.

In accordance with another aspect of the present invention, the innerliner may be formed by dip coating with a removable mandrel or it may bemade from PTFE.

The following terms: “aspiration”, “vacuum” and “suction” are commonlyused in this application, and all are related to using negative pressurethat generally pertains to the movement of blood clots and other tissuecaused by negative pressure.

The following terms endovascular catheter, aspiration catheter andcatheter have the same functional meaning, and all may be related to theremoval of plaque, tissue, blood clots, blood and other liquids from thehuman body, as well as being used to deliver medications, implants,therapeutic agents and other matters.

As used herein, “treatment site” refers to any location in the body thathas been or to be treated by methods or devices of the presentinvention. Although “treatment site” often refers to an endovasculararea including arteries and veins, the treatment site is not limited toendovascular tissue or blood clots. The treatment site may includetissues and blood clots associated with outside of endovascularlocation, including but not limited to bodily lumens, organs, ducts orlocalized tumors.

The treatment sites of the present invention involve blood vessels inthe patient's vasculature, including veins, arteries, aorta, heartvalves and particularly including cerebral, coronary and peripheralarteries, as well as previously implanted grafts, shunts, fistulas andthe like. In alternative embodiments, methods and devices to removeblood clots and other tissue described herein may also be applied, butare not limited to, the biliary duct, head, nerves, glands, and thelike.

The scope of the present invention is best defined by drawings,descriptions below and the appended claims. In certain instances,descriptions of vacuum physics, well-known devices, compositions,components, mechanisms and methods are omitted so as to not obscure thedescription of the present invention with unnecessary details.

Some theoretical considerations have been introduced in the presentinvention for assessing and exploring how these therapeutic methods areeffective. These considerations have been provided only for presentingan understanding of the invention only and have no relevance to orbearing on the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an extension catheter according to one embodiment ofthe present invention.

FIG. 2 illustrates an extension catheter according to another embodimentof the present invention.

FIG. 3 is a cross-sectional view of a catheter assembly for removal ofclots incorporating the extension catheter of FIG. 1.

FIG. 4 is an enlarged sectional view of the distal portion of a guidecatheter and the extension catheter of FIG. 1.

FIG. 5A illustrates another embodiment of the extension catheter with anexpandable tip.

FIG. 5B is an enlarged sectional view of the area C in FIG. 5A.

FIG. 6A illustrates the expandable tip of the tubular member of FIG. 5Ain a compressed configuration inside the distal end of the guidingcatheter.

FIG. 6B shows the distal end of the tubular member of FIG. 6A with theexpandable tip expanded and positioned adjacent blood clots that are tobe removed.

FIG. 7A is an enlarged sectional view of one embodiment of the area A/Bin FIG. 4.

FIG. 7B is an enlarged sectional view of another embodiment the area A/Bin FIG. 4.

FIG. 8 shows a cross section of an endovascular catheter having a hybridreinforcement with a braid surrounding a helical coil.

FIG. 9 illustrates the outer jacket of the catheter body.

FIG. 10 shows a device for removing blood clots.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates an extension catheter 100 that includes a tubularportion 101 and a pushing/pulling wire 102. The tubular portion 101 hasa distal end 103 and a proximal end 104. The wire 102 is attached to theproximal end 104 of the tubular portion 101 at a connection point 105.The extension catheter 100 has an outer lumen 106 and an inner lumen107. The tubular portion 101 may also include a reinforced wall 108. Oneradiopaque marker 109 is located on the distal end 103 of the tubularportion 101, and another radiopaque marker 110 is located on theproximal end 104 of the tubular portion 101. The tubular portion 101 ofthe extension catheter 100 may be 2-100 cm long, while the attachedpushing/pulling wire 102 may have any size and length suitable forinterventional procedures.

The tubular portion 101 may be constructed from any suitablebiocompatible plastics and elastomers used in medical devices exhibitingthe following characteristics: flexibility, durability, softness, andeasily conformable to the shape of the treatment and to minimize risk ofharm and trauma.

The tubular portion 101 may also include an inner liner (not shown). Theinner liner may be of a polymeric lubricious composition including butnot limited to polytetrafluoroethylene (TFE) polymer to reduce friction.The reinforcement 108 may include but is not limited to braid, coils,knit and combinations thereof. The materials of choice can be stainlesssteel, polymers and super-elastic alloys such as Nitinol.

The reinforcement 108 may be partially constructed of polymeric fibersor carbon fibers either replacing a portion of the metallicribbons/wires or polymeric materials or placed in conjunction with aribbon or wires in the braid. Other metals (e.g., noble metals such asmembers of the platinum group or gold) may be used in the braid itselfin much the same way to impart radiopacity to the braid. To tailor thestiffness of the braid, the braid may first be wound and portions of theribbon then removed. Also, the reinforcement 108 may be discontinuousleaving polymer alone without reinforcement.

Ribbons or wires making up the braid and coils can also contain a minoramount of other materials. Fibrous materials, both synthetic andnatural, may also be used. In certain applications, particularly smallerdiameter catheter sections, more malleable metals and alloys (e.g.,bold, platinum, palladium, rhodium, etc.) may be used. A platinum alloywith a few percent of tungsten is sometimes preferred partially becauseof its radiopacity. Suitable nonmetallic ribbons or wires includematerials such as those made of polyaramides (Kevlar), polyethyleneterephthalate (Dacron), or carbon fibers.

The pushing/pulling wire 102 attached to the tubular portion 101 of theextension catheter 100 may have variety of configurations including butnot limited to circular, oval, square, flat and combinations thereof.The wire 102 may be made with any suitable metal, preferably Nitinol,and may have a variety of tapered section(s) to provide a properflexibility and ability to pull and push the tubular portion 101 backand forth within the body or other catheters.

FIG. 2 shows an alternative configuration for the extension catheter200. The extension catheter 200 includes the tubular portion 201 and thepushing/pulling wire 202. The tubular portion 201 has a distal end 203and a proximal end 204. The wire 202 is connected to the proximal end204 of the tubular portion 201 at a connection point 205 and also isattached to the distal end 203 of the tubular portion 201 at anotherconnection point 206. Such connection of the wire 202 to the distal end206 and the proximal end 205 of the tubular portion 201 provides anadditional internal reinforcement within the tubular portion 201, andprovides better pushability of the tubular portion 201 when theextension catheter 200 is introduced into another catheter or navigatedinside the body. The extension catheter 200 has an outer lumen 208 andan inner lumen 207. One radiopaque marker 209 is located on the distalend 203 of the tubular portion 201, and another radiopaque marker 210 islocated on the proximal end 204 of the tubular portion 201.

The distal end 203 of the tubular portion 201 and the proximal end 204of the tubular portion 201 may have one of the following openings,including but not limited to circular, oval, elliptical, angulated,irregular shape or combinations thereof. A largest possible aperture orenlargement of the distal end 203 of the tubular portion 201 and/or onthe proximal end 204 of the tubular portion 201 will provide highersuction efficacy and better ability to remove blood clots and othertissue.

Coating of the external surface 211 of the tubular portion 201 of theextension catheter 200 may also be beneficial to reduce the friction ofthe extension catheter 200 but also to facilitate a seal between thetubular portion 201 of the extension catheter 200 and a guide catheter(not shown).

There are two most common coatings that may be used on the surface ofthe tubular portion 201 of the extension catheter 200: hydrophobiccoating and hydrophilic coating. Hydrophobic coatings offer coefficientsof friction in the range of approximately 0.15 to 0.3. In contrast,hydrophilic coatings are much more lubricious and have coefficients offriction in the range of 0.005 to 0.2. Hydrophilic coatings, by theirnature, must be wet in order to exhibit lubricity, while low frictionhydrophobic coatings do not need to be wet. In most cases, a dryhydrophobic coating is more lubricious than a dry hydrophilic coating.

A primary purpose of hydrophobic coatings such aspolytetrafluoroethylene or polyxylylene is to act as a barrier againstliquids. If a device must be sealed so that moisture, contrast, saline,blood do not get inside or between, one of these hydrophobic coatingswill work well to prevent liquids from or on the device's surface andact as a sealant over areas where liquid can penetrate.

Hydrophilic coatings imbibe water and most of them are in fact comprisedof more than 90% water when wet. However, most medical hydrophiliccoatings rely on primer coats or base coats for adhesion to a surface,and these primers tend to be relatively hydrophobic, which could causethem to act as liquid barriers and serve a seal between outer surface ofthe tubular portion 201 of the extension catheter 200 and anotherdevice.

Given the differences in functions, applications for hydrophobic andhydrophilic coatings are different, and some applications overlap. Thepresent invention may be one of the examples where both coatings may beadvantageous.

FIG. 3 shows a cross sectional view of a catheter assembly 300 forremoval of clots and other tissue. The catheter assembly 300 comprisesan extension catheter 301, a guide catheter 302 and a seal 303. Theextension catheter 301 can be the same as the extension catheter 101 ofFIG. 1, and is introduced inside the guide catheter 302 through theTouhy Borst 312. The extension catheter 301 comprises a tubular portion304 having a distal end 305 and proximal end 306. The pushing/pullingwire 307 is attached to the distal end 305 of the tubular member 304 atthe attachment area 308, and in this specific embodiment the wire 307 isattached to the proximal end 306 of the tubular member 304 at theattachment area 309. The manner in which the wire 307 is attached to thetubular member 304 improves pushability of the tubular member 304 whenintroduced into the guide catheter 302, and any other proceduralmanipulations to and at the treatment site. The distal end 305 of thetubular member 304 is positioned outside the guide catheter 302 whilethe proximal end 306 of the tubular member 306 is positioned inside theguide catheter 302. The guide catheter 302 comprises a soft tip 313located on its distal end, and a Y-connector 310 has an outlet arm 311that functions for suction attachment and the Touhy Borst 312.

The soft tip 313 provides a sealing feature, which under suction fromwithin the guide catheter 302 when suction is applied at the suctionport 311 folds around the tubular member 304 (not shown) and securesclosure around the guide catheter 302, thus creating vacuum along thetubular portion 304 of the extension catheter 301 and the guide catheter302. The seal area 303 is configured to allow a free movement of thetubular portion 304 of the extension catheter 301 within the guidecatheter 302. One radiopaque marker 314 is located on the distal end 305of the tubular portion 304 and another radiopaque marker 315 is locatedon the proximal end 306 of the tubular portion 304.

In the spirit of this invention, the tubular portion 304 of theextension catheter 301 is shorter than the length of the guide catheter302. The length of the tubular member 304 may be within 2-100 cm long,preferably 15-30 cm long.

Other options to seal the space between the tubular portion 304 of theextension catheter 302 and the guide catheter 302 may include additionalmember(s) either provided on the outer surface of the tubular portion304, or within the lumen of the guide catheter 302, or both. Althoughthe seal options have been described above with respect to certainembodiments, it will be appreciated that various changes, modificationsand alterations may be made to such above-described seal embodimentswithout departing from the spirit and scope of the present invention.

FIG. 4 shows the catheter assembly 400 with an enlarged distal viewinside the blood vessel 401. The catheter assembly 400 comprises anextension catheter 402 can be the same as the extension catheter 101 ofFIG. 1. The extension catheter 402 is positioned within the distal endof the guide catheter 403. The extension catheter 402 comprises atubular member 404 and a pushing/pulling wire 405 attached to thetubular member 404 at a proximal attachment area 406 and a distalattachment area 407. A lubricious coating 408 is formed on the outersurface of the tubular member 404. Such coating facilitates movement ofthe tubular member 404 within the guide catheter 403 and outside of theguide catheter 403 when within the vessel 401. The guide catheter 403has a soft tip 409 on its distal end which provides a less traumaticinterface against vessels and other tissue during introduction of theguide catheter into the body. During the placement of the catheterassembly 400 at the treatment side, when there is no aspiration applied,the soft tip 409 is in an “open” position, as shown in FIG. 7A.

When aspiration is applied at the proximal end of the guide catheter 403(at the port 311 as shown in FIG. 3), the aspiration is applied to allinner lumens of the catheter assembly 400 along the guide catheter 403and the tubular portion 404 of the extension catheter 401, as shown byarrows 410. Aspiration from within the catheter assembly 400 affects theclot 411 surrounding the distal end of the tubular portion 404. Underaspiration from within the catheter assembly 400, the clot 411 beginsentering the distal end of the tubular portion 404 of the extensioncatheter 402 as shown by arrows 410.

Once aspiration is applied to the proximal end of the guide catheter403, the clot 411 starts flowing into the distal end of the tubularportion 404 as shown by the arrows 410, and creates suction flowresistance. After blood clot(s) 411/412 enters the tubular portion 404of the extension catheter 401, vacuum pressure increases. The soft tip409 folds around the tubular portion 404 of the extension catheter 402and begins acting like a seal, as shown in FIG. 7B. With higheraspiration pressure within the catheter assembly 400, a better-yieldedseal is produced by the soft tip 409 against or around the guidecatheter 403. Also, a blood clot within the seal area (not shown) mayaid in providing a better seal.

In addition, the catheter assembly 400 has a unique configuration forthe inner aspiration lumens, with a larger inner lumen 413 within theguide catheter 403 than the inner lumen 414 within the tubular portion404 of the extension catheter 402. This unique configuration increasesthe flow of aspirated clots and improves the efficacy of clot removal.

FIG. 5A shows an extension catheter 500 according to another embodiment,where the extension catheter 500 comprises a tubular portion 501 and apushing wire 502. The tubular portion 501 has an expandable tip 503attached to the main body 504. The pushing wire 502 is attached to themain body 504 of the tubular portion 501 at an attachment area 505. Theexpandable tip 503 is located on the distal end of the tubular portion501 and is attached to the tubular portion 501 at an attachment area506. The expandable tip 503 has a funneled or conical configuration withthe very distal end 507 having a larger inner and outer dimension thanthe proximal end of the expandable tip 503. The expandable tip 503 isshown in an expanded configuration in FIGS. 5A and 5B.

The expandable tip 503 can be made of a tubular braid 508, is coated andhas its complete surface covered with silicone 509, as shown in FIG. 5B.The importance of the expandable tip 503 is the fact that the verydistal end 507 has an aperture 510 that has a larger diameter than thediameter of the main body 504. Such larger aperture on the distal end507 of the tubular member 501 significantly improves the efficacy ofblood clot removal.

The space or voids within the braid 508 are filled up and covered withsilicone 509, thus creating a shield that prevents penetration andsuction of blood clots through the outer surface of the expandable tip503. Therefore, it guarantees that the maximum vacuum pressure can beapplied at the aperture 510.

The tubular braid 508 may be made of a plurality of wires having sizesbetween 0.0005-0.0030 inches and the same or different inner/outerdimensions, and constructed of wire strands made of metals, alloys,polymers, Nitinol, cobalt-chromium alloys, Platinum, Platinum-Iridiumalloys, polymers or combinations thereof. The wire strands may be formedinto a tubular circular shape, tubular oval shape or any suitableshapes, and may be made using (but not limited to) circular wires, ovalwires, flat wires and combinations thereof.

The angle of the tubular braid 508 (i.e., angle between two crossingfilaments of the braid—not shown) plays an important role of easing theexpanding and collapsing braid. An easier-collapsing braid requires lessforce for pushing the braid through other restrictive tubes when in thecollapsed configuration; for example, pushing through the guidingcatheter. A small braid angle of less than 30 degrees in the collapsedconfiguration and less than 70 degrees in the expanded configurationwill be more amenable and would create less friction during introductionand manipulations within and outside of the guide catheter.

The radial size of the overall braid 508 in the expanded configurationmay have dimensions in any range between 0.5 mm-50 mm to assure properfit into the treatment area. The braid 508 of the expandable tip mayhave between 8 and 144 strands, and a variety of wire configurationsincluding, but not limited, to: one wire on one wire (1/1); one wire ontwo wires 1/2); two wires on two wires (2/2); two wires on one wire(2/1) and other suitable combinations.

Silicone or silicone rubbers are synthetic polymers containing silicontogether with carbon, hydrogen, oxygen, and are commonly used in medicaldevices and implants. One of the most unique mechanical properties ofsilicone rubbers are excellent elongation of 1000% or more, flexibilityand a durometer range of 5 to 80 Shore A. Such elongation and durometerranges will provide the braid 508 with a shield in the expanded andcollapsed configurations. It is important to mention that softer formsof silicone have the ability to retain their softness indefinitely.

The most common assembly methods for joining silicone components includeinsert molding and bonding. While insert molding process involvesinjection molding around an existing part, bonding normally entailsjoining silicone components with other polymers with adhesives. In thepresent invention, the silicone coat 509 is preferably applied on braid508 and within the braid 508 strands by dipping. Other silicone coveringmethods may include but are not limited to tipping and cuffing.

FIG. 6A shows an extension catheter 600 having a tubular member 601comprising an expandable tip 602 connected to a pushing wire 603 at aconnection area 604. The extension catheter 600 is shown inside theguiding catheter 605, and the extension catheter 600 can be the same asthe extension catheter 201 in FIG. 2. A soft tip 606 is located on thedistal end 607 of the guiding catheter 605. The tubular member 601 isshown within the guiding catheter 605 before deployment to the treatmentsite. The expandable tip 602 of the tubular member 601 is in acompressed configuration and exhibits a tubular shape. Once theexpandable tip 602 is pushed distally using the pusher wire 603 outsideof the guiding catheter 605 and leaves the distal end 607, theexpandable tip 602 will assume its expanded configuration 608 as shownin FIG. 6B.

FIG. 6B shows the extension catheter 600 as in FIG. 6A but partiallyoutside the distal end 607 of the guiding catheter 605. The expandabletip 602 is in the expanded configuration and has an enlarged distalaperture 609. The distal aperture 609 of the expandable tip 602 ispositioned at clots 610 to be removed from the vessel 611. Uponactivation of aspiration at the proximal end of the guiding catheter 605(not shown), suction of clots 610 begins inside the aperture 609 andalong the extension catheter 600 and the guide catheter 605.

Once suction of the clots 610 starts, vacuum pressure shown by arrows612 increases inside the extension catheter 600 and the guiding catheter605. Suction activation will cause the soft tip 606 of the guidingcatheter 605 to encircle the outer surface of the extension catheter600, and create a seal.

The distal expandable tip 602 opens to a larger inner lumen 609 than itsnormal lumen size upon release from the guide catheter 605 when insidethe guiding catheter 605. The tubular member 601 with a larger lumen 609of the expandable tip 602 will increase the efficacy of clot removal.

The tubular member 601 of the extension catheter 600 is configured to bepushed through and out of the guide catheter 605, and retrieved backinto the guide catheter 605 using the pushing wire 603, before bloodclot removal, during blood clot removal, after clot removal and duringremoval at combinations of these times.

The expandable tip 602 having a tubular braid and coated with siliconeis suitable to assume a pre-set expanded shape of any desired conicalconfiguration when pushed outside of the guide catheter 605.

The extension catheter with an expandable tip that is made of a tubularbraid and coated with silicone may be embodied in other forms andconfigurations without departing from the spirit of the presentinvention. Furthermore, the embodiments of the expandable tipillustrated in the present invention should be considered in all aspectsas illustrative and not restrictive and such expandable tip may also beimplemented in a conventional catheter and micro-catheter for anysuitable use to treat endovascular and outside of endovascular diseases,illnesses or disorders.

Braided and coiled shafts (also known as braid and coil reinforcedshafts) have been a trending topic in the world of medical cathetersrecently. With the growing popularity of complex minimally invasivesurgeries and the rising demands of the procedural requirements, theneed for shafts with tighter tolerances and improved characteristics hasincreased drastically. By utilizing braiding and coiling reinforcements,shafts can be provided with thinner walls while also improving thepushability, steerability, torque, and non-kinking features thatnon-reinforced shafts lack. With all approaches to tighten the wall ofthe catheters, a new challenge with catheter compression has arisen andneeds to be resolved. More specifically, when the catheter is pushedpercutaneously from outside the body to remote locations within thebody, often times more than 100 cm from the distal end of the catheter,it often causes a very distal portion of the catheter to compress orcreate an “accordion” which limits the catheter aspiration and otherperformance abilities. To address this challenge, a new catheter wallstructure is proposed.

FIG. 8 shows a cross section of an endovascular catheter 800. Thecatheter 800 has an elongate flexible catheter body 801 having a distalend 802, a proximal end 803, an inner central lumen 804 extendinglongitudinally through the catheter body 801, and a catheter wall 805.The catheter wall 805 comprises a tubular inner liner 806, a hybridreinforcement 807 and a variable durometer outer jacket 808, positionedin this order radially from the central lumen 804 to the exterior. Aradiopaque marker 809 is located at the proximity of the distal end 802,and a soft tip 810 is located at the very distal end 802 of the catheter800.

The distal tip 810 of the catheter body 801 is configured to berelatively atraumatic when it engages with tissue (e.g., vascular walls)of the patient, yet stiff enough to allow at least the distal opening811 to substantially maintain its cross-sectional shape, or otherwiseresist geometric deformation as the distal tip is maneuvered over aguidewire or another device (e.g., another catheter). The outer jacket808 of the catheter 800 defines an angled outer surface 813 that tapersvery distally from a diameter of the outer jacket 808 to a smaller outerdiameter 812 at the distal end 802 of the catheter 800. The angled outersurface 813 of the tip 810 is often referred to as a soft tip, and helpsto guide the distal tip 810 of catheter body 800 along a curved vascularwall and may help reduce adverse interactions between the distal tip 810of catheter body 800 and the vascular wall.

The radiopaque marker 809 is at least partially embedded in the outerjacket 808 and adhered to the distal end 814 of the hybrid reinforcement807. This arrangement prevents the distal end 814 of the hybridreinforcement from being exposed outside the outer jacket 808. Theradiopaque marker 809 may be bonded to the distal end 814 of the hybridreinforcement 807 and/or fused or heat shrunk to the inner liner 806.The radiopaque marker 809 may be formed from any suitable material, andmay be in the form of a continuous ring, a discontinuous ring, ormultiple segments that extend around the perimeter of the catheter body801. The radiopaque marker 809 is positioned to indicate the location ofthe distal tip 810 of the catheter body 801 and is located at theproximity of the distal opening 811.

The inner tubular liner 806 may be formed by dip coating on a removablemandrel or may be in the form of a tubular liner made of PTFE.Optionally, a tie layer surrounding the inner layer 806 (not shown) maybe added to provide a better bond when heat shrinking or bonding layersof the catheter wall 805. The tie layer may be made of polyurethane andhave a wall thickness of no more than about 0.004 inches, and may extendalong at least 3 cm or more from the distal end 809 of the catheter body801.

The inner liner 806 may be comprised of two or more longitudinalsegments (not shown). The first distal segment of the inner liner 806may be made of PTFE to provide distal inner lubricity, while at leastone proximally adjacent segment may be made of, but is not limited to,urethane or polyurethane elastomer or other polymers, to increase thestiffness of the proximal portion of the catheter 800. The length of thedistal segment of the inner liner 806 may be 1-25 inches, and the lengthof the proximally adjacent segment of the inner liner 806 may have alength of 1-80 inches. Alternatively, the inner liner 806 may beterminated before the distal end of the catheter 800 to improve theflexibility of the distal end of the catheter 800. The inner liner 806may be made of, but is not limited to, urethane, polyurethane or othersimilar materials. The length of the distal segment of the inner liner806 may be between 5-50 cm, and preferably 10-20 cm.

The hybrid reinforcement 807 comprises a helical coil 815 and a braid816 overlying each other. The helical coil 815 surrounds the inner liner806 when viewed radially from the inner liner 806 towards the outerjacket 808. The braid 816 encircles or overlaps the helical coil 815.The helical coil 815 may be made or formed from a stainless steel or ashape memory alloy (SMA) wire, rounded or flat, with a constant orvariable pitch and the desired diameters, and include a taperedconfiguration if needed. The layout of the helical coil 815 may beadjusted to achieve the desired pitch profile (e.g., the change in pitchover the length). The SMA is an alloy that “remembers” its originalshape and when deformed returns to its pre-deformed shape when heated.The SMA preferably comprises an Austenite state at body temperature.

The braid 816 may be formed from a plurality of wire strands having adimension that is between about 0.0003 inches and about 0.010 inches,and made of one of the following materials: metals, alloys, shape memorymaterial (e.g., Nitinol), cobalt-chromium alloys, Platinum,Platinum-Iridium alloys, polymers (e.g., Nylon, Polyester, etc.), or anycombination thereof. The braid 816 may include strands of the samedimensions or of different dimensions that are braided using a circularwire, oval wire, flat wire or any other suitable wire configuration.

The configurations for the hybrid reinforcement 807 may include anydesirable structure made of both its components (coil and braid). Forexample, the configurations for the helical coil 815 may includevariable pitch, variable wire size, different outside diameterdimensions, or tapered configuration. The braid 816 may be made in anydesirable configuration as listed in the paragraph above. Alternatively,the hybrid reinforcement may have the same structure along the entirelength of the catheter 800 with the same helical coil configuration andthe same braid.

FIG. 8 shows the hybrid reinforcement 807 comprising the helical coil815 surrounding the inner liner 806 and the braid 816 surrounding thehelical coil 815. Alternatively, the structure of the hybridreinforcement 807 may be reversed with the braid 816 surrounding theinner liner 806 and the helical coil 815 surrounding the braid 816 (notshown)

The distal end of the coil 815 and the distal end of the braid 816 maybe covered by the distal marker 809. The distal end of the coil 815 maybe terminated more distally than the overlapping braid or moreproximally than overlapping braid (not shown).

Alternatively, the hybrid reinforcement 807 may comprise a braidsurrounding the inner layer, and a helical coil surrounding the braid(not shown). The braid may be terminated more distally than theoverlapping coil or more proximally than the overlapping coil (notshown).

The structure of the catheter 800, especially the construction of thehybrid reinforcement 807, provides all needed catheter performancecharacteristics, such as: strength, flexibility, kink resistance,torque, shape retention, and compression resistance. The structure alsoprovides a good integrity of the overall catheter 800 with the overallcatheter 800 having a tensile strength higher than 2 lbs., as well as atrue 1:1 push/pull while tracking through tortuous anatomy. It is alsoimportant to maintain a large inner diameter defined by the catheterwall thickness ratio: the inner diameter to the outer diameter of thecatheter 800. It is desirable that the catheter wall thickness ratio is0.80 or higher.

FIG. 9 illustrates the outer jacket 808 of the catheter body 801. Whilethe outer jacket 808 may be formed of multiple segments, the catheter800 shown in FIG. 9 is made of five discrete tubular segments, as anexample. The segment 51 is the most flexible and may be made from Pebax2533, among other possible materials. The other segments 52, 53 and 54are all preferably made from Pebax 3533, although other materials arealso possible. The segment 55 is also preferably made from Pebax 6533 or7533, although other materials are also possible. The outer jacket maybe formed from at least two, and as many as twenty or more, discretetubular segments. The difference in durometer between the tubularsegments may be at least about 5 D. The durometer difference between thevery proximal and the very distal tubular segments may be at least about30 D.

The outer jacket 808 is made of polymers with several segments of avariable durometer, with a lower durometer segment usually located onthe distal end and higher durometer segments located progressivelyproximally along the catheter length. The segments of variableflexibility may be made from, but are not limited to, the followingmaterials: Tecoflex EG-80A; Tecoflex EG-85A; Pebax 2533, Pebax 3533,Pebax MX1205; Pebax5533, Pebax 6433; Pebax 7233, Nylon 6, Nylon 12 andany combination thereof.

For increasing the tension resistance in the distal zone of the catheter800, a support filament may be carried between the inner liner 806 andthe hybrid reinforcement 807, or within the helical coil 815 and thebraid 816 (not shown). The axially extending filament may increase thetensile strength of the catheter 800 to at least three or more pounds.The filament material may include, but is not limited to, Vectren,Dacron or Kevlar fibers.

FIG. 10 shows another aspect of the present invention, where a device1000 includes an aspiration catheter 1001 having a distal end 1002 and aproximal end 1003; and a liquid aspiration pump 1004 attached via a tube1005 to the proximal end 1003 of the aspiration catheter 1001. Theliquid aspiration pump 1004 is attached to the blood collecting bag1006. The liquid aspiration pump 1004 functions to directly remove bloodclots and other tissue from the body, unlike commonly-used airaspiration pumps that use air suction from inside the blood container toaspirate clots and other tissue. Cycling of the liquid aspiration pump1004 may further enhance efficacy to remove clots. Higher clotrecanalization rates may be achieved by cyclic aspiration at 3-10 Hz,which in experimental work has outperformed static aspiration whenliquid medium is used to aspirate clots.

To secure maximum clot removal efficacy, the aspiration catheter 1001should have the largest inner diameter and a thin wall to be compliantwith the limiting inner diameters of introducer sheaths and guidingcatheters that are commonly used in the most interventional procedures.However, to secure catheter performance characteristics andcompatibility with introducer sheaths and guiding catheter, it isadvantageous that the ratio R of the catheter inner lumen diameter ID tothe catheter outer lumen diameter OD should be more than 0.80.

The liquid aspiration pump 1004 has mechanically actuated positivedisplacement powered by a rotating motor incorporated in the pumpassembly (not shown) and may be powered by line power or battery. It isdesirable to cycle the rotating motor at less than 10 Hz frequency whilemaintaining the motor speed below 2000 RPM to achieve the best efficacyto remove clots and other liquids. Cycling of the liquid aspiration pump1004 will cause the pump aspiration pressure to continuously change upand down, and produce a pulsating effect on blood clots to be removed.Such blood clot pulsation will disrupt or break the structure of bloodclots and prevent the aspiration catheter 1001 from clogging. The logicbehind this approach is that cycling pressure/forces will induce fatigueon the blood clots or other tissue to be removed, thereby enabling theremoval of more entrenched blood clots and prevent catheter clogging.

Although this invention has been described with reference to preferredembodiments and examples, those having ordinary skill in this art willrecognize that changes may be made in form and detail without departingfrom the spirit and scope of the invention as found in the claims whichfollow.

What is claimed is:
 1. An endovascular catheter comprising: an elongateflexible catheter body having a proximal end, a distal end and a centrallumen extending longitudinally through the catheter body, wherein thecatheter body comprises a catheter wall that has an inner liner, ahybrid reinforcement and a variable durometer outer jacket, wherein thehybrid reinforcement comprises a helical coil and a braid overlappingeach other, and wherein the catheter wall has an inner diameter and anouter diameter, and a thickness ratio of the inner diameter to the outerdiameter is 0.80 or higher.
 2. The catheter of claim 1, wherein tensilestrength of the catheter is higher than 2 lbs.
 3. The catheter of claim1, wherein a radiopaque marker is fully encapsulated on the distal endbetween the inner liner and the outer jacket, and the hybridreinforcement has a distal end, and wherein the radiopaque markerpartially covers the distal end of the hybrid reinforcement.
 4. Thecatheter of claim 1, wherein inner liner comprises PTFE which terminatesat least 5 cm from the distal end of the catheter body.
 5. The catheterof claim 1, wherein the structure of the hybrid reinforcement is thesame along the length of the catheter body.
 6. The catheter of claim 1,wherein the braid is positioned over the helical coil.
 7. The catheterof claim 6, wherein each of the helical coil and the braid has a distalend, and the distal end of the helical coil and the distal end of thebraid are covered by the distal marker.
 8. The catheter of claim 6,wherein the helical coil terminates more distally than the braid.
 9. Thecatheter of claim 6, wherein the helical coil terminates more proximallythan the braid.
 10. The catheter of claim 1, wherein the hybridreinforcement comprises a braid positioned over the inner layer andwherein the helical coil is positioned over the braid.
 11. The catheterof claim 6, wherein the braid terminates more distally than the helicalcoil.
 12. The catheter of claim 6, wherein the braid terminates moreproximally than the helical coil.
 13. The catheter of claim 1, whereinthe catheter has a push/pull ratio while tracking through endovascularanatomy, and the push/pull ratio is 1:1.
 14. A device for removing bloodclots, comprising: an endovascular catheter having at least one lumen, adistal end and a proximal end, the catheter having an inner lumen and anouter lumen, each of the inner lumen and the outer lumen having adiameter, and wherein ratio of the diameter of the inner lumen to thediameter of the outer lumen is more than 0.80; and a liquid aspirationpump attached to the proximal end of the catheter and having a motor,and a mechanically actuated positive displacement powered by rotatingthe motor, wherein the motor rotates at a speed below 2000 RPM whendriving the aspiration pump and wherein the speed of the motor is cycledat a frequency below 10 Hz.